Tropical Depression ELEVEN

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TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112013
1100 PM AST SAT SEP 28 2013
THE WELL-DEFINED AREA OF LOW PRESSURE OVER THE CENTRAL ATLANTIC HAS
DEVELOPED ENOUGH ORGANIZED DEEP CONVECTION TO BE CLASSIFIED AS A
TROPICAL DEPRESSION...THE ELEVENTH ONE OF THE ATLANTIC HURRICANE
SEASON. THE INITIAL WIND SPEED IS SET AT 30 KT BASED ON EARLIER
SCATTEROMETER DATA.
THE DEPRESSION IS MOVING NORTHWARD AT ABOUT 8 KT ON THE WEST SIDE OF
A DEEP-LAYER RIDGE. THIS SUBTROPICAL RIDGE IS EXPECTED TO WEAKEN
SOON AS A LARGE TROUGH AMPLIFIES OVER THE NORTH ATLANTIC...CAUSING
THE CYCLONE TO TURN NORTHEASTWARD OVERNIGHT AND THEN EASTWARD LATE
SUNDAY. THE TROUGH IS NOT EXPECTED TO ABSORB OR PICK UP THE
DEPRESSION...INSTEAD THE MODELS ARE IN GOOD AGREEMENT IN SHOWING
THE CYCLONE BEING LEFT BEHIND IN WEAK STEERING CURRENTS FOR AT LEAST
A FEW DAYS. THE NEXT SUBSTANTIAL INFLUENCE ON THE STEERING FLOW
WILL LIKELY BE ANOTHER TROUGH THAT WILL BE APPROACHING THE
DEPRESSION AROUND THE MIDDLE PORTION OF NEXT WEEK. THE NHC FORECAST
SHOWS THE SYSTEM MAKING A CLOCKWISE LOOP AND LIES CLOSE TO THE
DYNAMICAL MODEL CONSENSUS THROUGH THE FORECAST PERIOD.
THE DEPRESSION IS CURRENTLY BEING AFFECTED BY ABOUT 15 KT OF
SOUTHERLY SHEAR...WHICH HAS DISPLACED MUCH OF THE ASSOCIATED
CONVECTION TO THE NORTH OF THE CENTER. THE SHEAR IS EXPECTED TO
LESSEN DURING THE NEXT 24 HOURS...WHICH SHOULD ALLOW THE DEPRESSION
STRENGTHEN A LITTLE. AFTER THAT TIME...HOWEVER...AN INCREASE IN
NORTHWESTERLY SHEAR AND DRIER AIR ARE EXPECTED TO END THE
STRENGTHENING TREND AND LIKELY INDUCE WEAKENING. THE NHC WIND
SPEED FORECAST IS NEAR THE INTENSITY MODEL CONSENSUS IN THE SHORT
TERM AND THEN LIES ON THE LOW SIDE OF THE GUIDANCE GIVEN THE
ANTICIPATED HOSTILE ENVIRONMENTAL CONDITIONS.
FORECAST POSITIONS AND MAX WINDS
INIT 29/0300Z 25.2N 50.2W 30 KT 35 MPH
12H 29/1200Z 26.1N 49.4W 35 KT 40 MPH
24H 30/0000Z 27.0N 48.3W 40 KT 45 MPH
36H 30/1200Z 27.1N 47.0W 40 KT 45 MPH
48H 01/0000Z 26.6N 46.5W 40 KT 45 MPH
72H 02/0000Z 26.2N 47.5W 35 KT 40 MPH
96H 03/0000Z 27.2N 49.0W 35 KT 40 MPH
120H 04/0000Z 29.5N 47.5W 30 KT 35 MPH
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FORECASTER CANGIALOSI
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